In electrical connector design, miniaturization has become an increasingly important consideration. However, there is a trade off between connector performance and reduced size. As the size of the connector is reduced, less space is available within the receptacle housing of the connector for a connector beam. Such a limited space makes it increasingly difficult to provide a low pin insertion force relative to a high normal retention force, while maintaining the desirable tolerances of the connector structure.
In a compact connector, the above-mentioned low insertion force is a significant design factor. As the area required for each pin-to-beam contact is reduced, more contacts may be placed in the connector. Heretofore, more force was necessary for inserting a component within such a connector. Such increased insertion force, particularly where the connector is mounted on a printed circuit board, can result in an unreliable connection, bending of the printed board and solder joint cracking.
Cantilever beams have been used in the art to provide low insertion force. The cantilever beam is generally supported only by one end so that the other end can move during a pin insertion cycle and the beam is thin in order to provide for the necessary deflection. When a pin is initially inserted into a connector housing, the pin touches the movable end of the beam. When the pin is inserted further, the movable end is pushed away in a direction that is substantially transverse to the pin insertion axis to accommodate penetration of the pin. This movement allows low insertion force for an easy insertion. However, when the pin is completely inserted into the connector, such a thin cantilever beam does not apply a desirably high normal force against the inserted pin in order to retain the pin in the connector housing.
On the other hand, a supported beam provides high normal force against a completely inserted pin. Since the supported beam is generally supported by both ends, unlike a cantilever beam, either end of the supported beam does not move. During the pin insertion cycle, the supported beam only deflects. Accordingly, the supported beam tends to require high insertion force during an initial phase of an insertion cycle. Since a compact connector assembly may accommodate a large number of contacts, the total amount of necessary insertion force is undesirably high.
Thus, neither a cantilever beam nor a supported beam alone may be appropriate for a compact connector. A cantilever beam may require low initial insertion force, but it may provide sufficient normal retention force against a completely inserted pin. A cantilever beam also requires a larger space for the movable end. A supported beam, on the other hand, may provide sufficient normal force against an inserted pin, but requires large insertion force during an initial phase of an insertion cycle. Accordingly, a large number of pins cannot be placed on the same connector with supported beams due to the larger insertion force.
Regarding the header of such a miniature connector, during the manufacturing process it is paramount that the terminal pins be aligned within the desired tolerances. Thus, upon connection of the header and receptacle the pins can be simply placed in the corresponding openings in the receptacle housing without any excessive force which could damage or break the miniature connector.
Thus, there is a need for an electrical connector wherein a relatively low force is necessary to insert a pin in the connector housing for electrical connection to a printed substrate or the like and wherein a spring beam contact applies a relatively high normal force against the pin for retaining the pin in the connector housing. The present invention provides an electrical connector which satisfies this need.